I gave the first dashcat5 mock test without any prep and have pathetically scored a 45 as overall marks. Should I even attempt CAT 2017?

Actually its your first attempt. As you go on preparing and write more mocks you will improve very well. Many toppers are also havent scored well in their mocks. Its a consistency game. Prepare more and write again. 

Don't be disheartened Aashka. Keep taking mocks regularly, you will surely improve. Also work on improving your concepts. There is a lot of time left. This is when you should start preparing.

Yes, thats why we need practice.

It's just the beginning. Prep well and then again sit for another mock after two months.. you will get an answer all by yourself..